Typewriter carriage decelerator

ABSTRACT

A first lever has a roller at one end engageable with the typewriter carriage during its carriage return stroke and a second lever has a pad at one end also engageable with the carriage. The first and second levers are connected together by a pin on the first lever slidable in a slot in the second lever, and a toggle spring urges the levers to one of two positions on either side of an overcenter position. The carriage engages with the roller of the first lever causing the levers to rotate thereby absorbing energy to decelerate the carriage. The levers move past the overcenter position so that the roller disengages from the carriage and the pad, which was initially positioned out of the path of the carriage, is moved in front of the carriage. The carriage engages with the pad and rotates the levers past the overcenter position to their initial positions thereby absorbing more energy and further decelerating the carriage. The carriage is finally stopped by a fixed resilient stop member.

United States Patent 1191 Iwasaki 1 1 Dec. 2, 1975 1 1 TYPEWRITER CARRIAGE DECELERATOR [75] Inventor: Kyuhachiro lwasaki, Tokyo, Japan [73] Assignee: Ricoh Co., Ltd., Tokyo, Japan [22] Filed: May 8, 1974 211 App]. No.: 468,076

[30] Foreign Application Priority Data May 14, 1973 Japan 48-53325 [52] US. Cl 197/64; 197/183 [51] Int. Cl. [58] Field of Search B4lJ 19/02 197/64, 183

Primary E.\'aminerErnest T. Wright, Jr. Attorney, Agent, or FirmCooper, Dunham, Clark, Griffin & Moran [57] ABSTRACT A first lever has a roller at one end engageable with the typewriter carriage during its carriage return stroke and a second lever has a pad at one end also engageable with the carriage. The first and second levers are connected together by a pin on the first lever slidable in a slot in the second lever, and a toggle spring urges the levers to one of two positions on either side of an overcenter position. The carriage cngages with the roller of the first lever causing the levers to rotate thereby absorbing energy to decelerate the carriage. The levers move past the overcenter position so that the roller disengages from the carriage and the pad, which was initially positioned out of the path of the carriage, is moved in front of the carriage. The carriage engages with the pad and rotates the levers past the overcenter position to their initial positions thereby absorbing more energy and further decelerating the carriage. The carriage is finally stopped by a fixed resilient stop member.

10 Claims, 2 Drawing Figures Sheet 1 of2 U.S.- Patent Dec. 2, 1975 U.s. Patent De.2,1975 sheetzofz 3,923,140

TYPEWRITER CARRIAGE DECELERATOR BACKGROUND OF THE INVENTION The present invention relates to a decelerating mechanism to gradually decelerate a body, such as a carriage or printing head of a typewriter to a stop.

As is well known, the carriage or printing head of a printer or typewriter has a relatively large mass which causes a large shock to be developed when it returns to its initial position during the carriage return stroke. Such a shock causes adverse effects such as the generation of noise and the reduction of the useful life of the printing head and other mechanical parts. A prior art means to eliminate such shocks comprises a buffer spring or rubber member, either alone or in-combination with a cushioning air cylinder such that the kinetic energy of the printing head is transmitted to the buffer spring through a linkage or lever. However, such means generally have drawbacks in that the absorption of kinetic energy from the printing head takes place rapidly to cause the development of secondary shocks or in that a relatively large space is required.

It is an object of the present invention to provide a decelerating mechanism especially suited to a carriage or printing head of a typewriter which is compact and decelerates the carriage gradually to prevent shocks.

The above and other objects, features and advantages of the present invention will become clear from the following detailed description taken with the accompanying drawing, in which;

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a plan view of a decelerating mechanism according to one embodiment of the present invention, in a first operative position; and

FIG. 2 is similar to FIG. 1 but shows the mechanism in a second operative position.

DETAILED DESCRIPTION OF THE INVENTION Referring now to the drawing, a movable body 1, such as a carriage or printing head of a typewriter or printer, is slidably mounted on a guide track 2 so as to be movable back and forth in a predetermined direction. The movable body 1 is arranged to move to the left (printing direction) a rather slow speed, and upon reaching the extreme left limit of its movement (not shown) to return to the right (carriage return stroke direction) at a relatively high speed until its initial position is reached. An engaging member 3 having projections 3a and 3b is secured to the bottom of the movable body 1 as by screws 4. A first lever member 5 is rotatably mounted at a pivot 6 to a fixed mounting plate 7, and rotatably carries a roller 8 at one end. The roller 8 is engageable with the projection 3a of the engaging member 3, and is formed of a resilient material such as hard rubber. A mass 9 for increasing the moment of inertia of the first member 5 is adjustably fixed to the other end of the first member 5 by means of a screw 11 which extends through an elongated slot 5a formed through the member 5. The lower edge of the first member 5 is engageable with a resilient pad 12 which is secured to a stop 13, which is in turn fixedly mounted to the mounting plate 7 by means of a screw 14.

The first member 5 is partially channel-shaped, and a pin 15 is fixed to one side plate 5b thereof. An overcenter biasing means or toggle 16 in the form of an open ring has one end connected to the pin 15 and its other end connected to a pin 17 which is fixedly mounted to the mounting plate 7. The spring 16 urges the first member 5 to rotate counterclockwise, as viewed in Flg. 1, into engagement with the pad 12 of the stop 13. The pin 15 slidably extends through a guide slot 18a formed through one end of a second lever member 18 which is rotatably mounted at pivot 19 to the mounting plate 7. A resilient pad 21 is secured to the other end of the second member 18 for engagement with the projection 3b of the engaging member 3. A stop 22 is disposed below the second member 18 and is secured to the mounting plate 7 by means of screw 23 for limiting the extent of rotation of the second member 18. A resilient pad 24 is secured to the stop 22. At the initial position or rightlimit of travel of the movable body 1, there is provided a resilient stop member 25 formed of an elastic material such as hard rubber, and mounted on fixed member 26 at a predetermined position.

When the movable body 1 returns to its right limit position moving in the direction of an arrow 27 at a relatively high speed, the speed at which it engages with the roller depends on the position from which it starts its return motion, and is also influenced to a certain degr'ee by variations in lubrication with temperature as well as variations in the frictional resistance with wear between the movable body 1 and the guide track 2. In FIG. 1, the pin 15 of the first member 5 is located slighly above an overcenter line 20 joining the pivot 19 of the second member 18 and the fixed pin 17 when the roller 8 is first engaged by the projection 3a of the engaging member 3. When the angle through which the first member 5 rotates is small so that the pin 15 does not move below the overcenter line, the member 5 will return to its first position shown in FIG. 1. When the angle through which the first member 5 rotates is large, both members 5 and 18 will be rotated to such an extent that the second member 18 abuts against the pad 24. Thus, the first and second members 5 and 18 are maintained in first positions shown in FIG. 1 or in second positions shown in solid lines in FIG. 2 by the action of the spring 16.

When the movable body 1 returns in the direction indicated by the arrow 27, the projection 3a of the engaging member 3 engages with the roller 8, rotating the first member 5 clockwise as viewed in FIG. 2. If the return speed of the movable body 1 is above a predetermined value, the impact shock imparted to the first member 5 will be great enough to cause it to rotate through an overcenter position at which the pin 15 lies on the overcenter line 20. The rotation of the first member 5 and the interlocked second member 18 is stopped by the abutment of the lower edge of the second member 18 against the pad 24, as shown in FIG. 2. Since the mass 9 is mounted on the end of the first member 5, the moment of inertia of the first member 5 about the pivot 6 is high, so that much of the kinetic energy of the movable body 1 is absorbed by the initial rotation of the first member to decelerate the body.

When the roller 8 of the first member 5 is moved from the first position shown in FIG. 1 to the second position shown in FIG. 2 and is cleared by the body 1, the pad 21 of the second member 18 moves into the path of movement of the engaging member 3, as shown in FIG. 2. As the projection 31; of the engaging member 3 engages with the pad 21, second member 18 will be rotated to its first position, shown in phantom lines in FIG. 2, from the second position indicated in solid lines. During this rotation, the first member 5 rotates with the second member 18, and a large amount of kinetic energy is absorbed in rotating the members 5 and 18 rapidly to further decelerate the body 1. In this manner, during the return movement of the movable body 1, the engaging member 3 engages with the first and second members 5 and 18 in two steps, and most of the kinetic energy of the movable body 1 is absorbed in causing reciprocatory rotary motion of the first member 5 which has a large moment of inertia. The amount of kinetic energy absorbed by the mechanism depends on the angle of the leading edge of the projection 3a.

The decelerated movable body 1, with its kinetic energy greatly reduced, is stopped by the stop member 25. When the speed at which the movable body 1 engages with the roller 8 is below the predetermined value, the first member 5 will be moved to an intermediate position between the first and overcenter posi' tions and returned to the first position shown in FIG. 1

after the body 1 clears the roller 8. Kinetic energy will be absorbed due to the rotation of the first and second members 5 and 18 against the force of the spring 16.

The movable body 1, having its kinetic energy and speed reduced, will come to a stop against the stop member 25 without engaging with the second member 18. In the initial position, the roller 8 will be held against a left beveled surface 3c of the projection 3a of the engaging member 3 by the force of the spring 16,

thus maintaining the movable body 1 in its rightmost initial or limit position.

It will be appreciated that the present invention permits the kinetic energy of the movable body 1 to be absorbed gradually depending on the speed thereof, by means of a simple and compact mechanism. High precision as used in a conventional decelerating mechanism incorporating an air cylinder is not required. The movable body is also maintained in its initial position and prevented from rebounding by the mechanism.

I claim:

1. A mechanism for decelerating a body movable in a predetermined direction, comprising:

a first member pivotal about a fixed point between a first position in which the body engages with a part of the first member and a second position in which the body clears the first member during movement of the body in the predetermined direction;

a second member pivotal about another fixed point between a first position in which the body clears the second member and a second position in which the body engages with a part of the second member during movement of the body in the predetermined di-' rection, the first and second members being connected together so that when the first member is in its first position the second member is in its first position and when the first member is in its second position the second member is in its second position; and

overcenter biasing means to urge the first member toward its first and second positions from an overcenter position between the first and second positions, the first and second members being initially in their respective first positions and the body engaging dur ing its movement in the predetermined direction with the part of the first member to pivot the first member past its overcenter position to its second position and thereby move the second member to its second position, the body engaging subsequently with the part of the second member to pivot the second member to its second position and thereby the first member past its overcenter position to its second position.

2. The mechanism according to claim 1, in which the body is a printer carriage and the predetermined direction is the carriage return direction.

3. The mechanism according to claim 1, in which the moment of inertia of the first and second members, the force of the overcenter biasing means and the overcenter position of the first member are selected so that the first member will be moved by the body from its first position to its second position past the overcenter position only when the body engages with the part of the first member at a speed faster than a predetermined speed, and when the body engages with the part of the first member at a speed slower than the predetermined speed, the body will move the first member from its first position to an intermediate position between its first and overcenter positions, the overcenter biasing means moving the first member from its intermediate position to its first position when the body clears the first member during its movement in the predetermined direction.

4. The mechanism according to claim 1, in which the first member comprises a lever, the part of the first member with which the body engages being a roller pivotally connected to one end of the lever.

5. The mechanism according to claim 1, in which the first member comprises a lever and a mass adjustably connected to the lever.

6. The mechanism according to claim 1, further comprising resilient stops engageable with the first and second members to prevent movement thereof past their respective first and second positions.

7, The mechanism according to claim 1, in which one of the first and second members is formed with a slot, and in which the other of the first and second members comprises a pin slidable in the slot.

8. The mechanism according to claim 7, in which the overcenter biasing means is a toggle spring having one end connected to a fixed point and the other end connected to the pin.

9. The mechanism according to claim 1, further comprising a resilient stop, the body being abutable against the resilient stop after engaging with the first and second members to be stopped thereby at a predetermined position.

10. The mechanism according to claim 9, in which the body is formed with a first part engageable with the part of the first member during movement of the body in the predetermined direction and a second part engageable with the part of the first member after the body is stopped in the predetermined position by the resilient stop, the force of the overcenter biasing means acting on the first member to maintain the part of the first member in engagement with the second part of the I body to hold the body in the predetermined position. 

1. A mechanism for decelerating a body movable in a predetermined direction, comprising: a first member pivotal about a fixed point between a first position in which the body engages with a part of the first member and a second position in which the body clears the first member during movement of the body in the predetermined direction; a second member pivotal about another fixed point between a first position in which the body clears the second member and a second position in which the body engages with a part of the second member during movement of the body in the predetermined direction, the first and second members being connected together so that when the first member is in its first position the second member is in its first position and when the first member is in its second position the second member is in its second position; and overcenter biasing means to urge the first member toward its first and second positions from an overcenter position between the first and second positions, the first and second members being initially in their respective first positions and the body engaging during its movement in the predetermined direction with the part of the first member to pivot the first member past its overcenter position to its second position and thereby move the second member to its second position, the body engaging subsequently with the part of the second member to pivot the second member to its second position and thereby the first member past its overcenter position to its second position.
 2. The mechanism according to claim 1, in which the body is a printer carriage and the predetermined direction is the carriage return direction.
 3. The mechanism according to claim 1, in which the moment of inertia of the first and second members, the force of the overcenter biasing means and the overcenter position of the first member are selected so that the first member will be moved by the body from its first position to its second position past the overcenter position only when the body engages with the part of the first member at a speed faster than a predetermined speed, and when the body engages with the part of the first member at a speed slower than the predetermined speed, the body will move the first member from its first position to an intermediate position between its first and overcenter positions, the overcenter biasing means moving the first member from its intermediate position to its first position when the body clears the first member during its movement in the predetermined direction.
 4. The mechanism according to claim 1, in which the first member comprises a lever, the part of the first member with which the body engages being a roller pivotally connected to one end of the lever.
 5. The mechanism according to claim 1, in which the first member comprises a lever and a mass adjustably connected to the lever.
 6. The mechanism according to claim 1, further comprising resilient stops engageable with the first and second members to prevent movement thereof past their respective first and second positions.
 7. The mechanism according to claim 1, in which one of the first and second members is formed with a slot, and in which the other of the first and second members comprises a pin slidable in the slot.
 8. The mechanism according to claim 7, in which the overcenter biasing means is a toggle spring having one end connected to a fixed point and the other end connected to the pin.
 9. The mechanism according to claim 1, further comprising a resilient stop, the body being abutable against the resilient stop after engaging with the first and second members to be stopped thereby at a predetermined position.
 10. The mechanism according to claim 9, in which the body is formed with a first part engageable with the part of the first member during movement of the body in the predetermined direction and a second part engageable with the part of the first member after the body is stopped in the predetermined position by the resilient stop, the force of the overcenter biasing means acting on the first member to maintain the part of the first member in engagement with the second part of the body to hold the body in the predetermined position. 